Conventionally, there has been known an energy storage apparatus where a plurality of energy storage devices are housed in the inside of an outer case (see JP 2010-80450 A, for example). In such an energy storage apparatus, a plurality of energy storage devices (unit batteries) are housed in the inside of the outer case (case) having partitions therein. When an external force is applied to the energy storage apparatus, the irregular deformation of the entire outer case is prevented by the partitions thus enhancing safety of the energy storage devices.
However, in the above-mentioned conventional energy storage apparatus, depending on an external force applied to the energy storage apparatus, there exists a problem that the energy storage devices may not be properly protected. That is, in the above-mentioned conventional energy storage apparatus, although the irregular deformation of the entire outer case can be prevented by the partitions, when an external force is applied to a certain surface of the outer case in a concentrated manner or the like, there is a possibility that such a surface is damaged including deformation. In this case, there is a possibility that the energy storage device which is arranged in an opposedly facing manner with such a surface is damaged.